Two interesting articles related to epigenetics

These are two interesting articles I found one from the other

This one
https://www.mdpi.com/2073-4409/11/3/468/htm
Has a detailed look at the links between epigenetics and ageing. I personally think one aspect of epigenetics is "use it or lose it" that if a protein is being encoded for then it is more likely that this will remain available as a route to encoding, 
but if a protein is not encoded for then there is a good chance that the gene will end up methylated (or something like that).  Otherwise there is an epigentic dynamic going on.

This one 
https://www.nature.com/articles/s43587-021-00105-8
Is particularly interesting to me as it looks at the reason why older people don't have as many osteoblasts. It is known that higher levels of Melatonin overcome this issue and I am trying to understand the interplay between acetyl-CoA, Melatonin, HIF at the 
start of the citric acid cycle.  I will have a good look at this article and its references.